PURPOSE To examine the role of Drosophila optomotor blind (omb)-related T-box genes in development of human and mouse retina. METHODS Mouse Tbx2, Tbx3, and Tbx5 and human TBX2 cDNAs were isolated from retinal cDNA libraries by hybridization to the Drosophila omb gene. Gene expression patterns in developing retina were analyzed by in situ hybridization. RESULTS TBX2/Tbx2, TBX3/Tbx3, and TBX5...

holt-oram syndrome (hos) is a developmental disorder inherited in an autosomal-dominant pattern. affected organs are the heart and forelimbs with upper extremity skeletal defects and congenital heart malformation. in this study we present three cases of hos in the same family. in one of these three individuals we detected a transition of c to t (ctg-gtt, v205v) in exon 7 of the tbx5 gene. this ...

Genes required for limb developm ent have, in several instances, first been identified by studies of human diseases in which the limbs are affected. In humans, m utations in the transcription factor SALL4 results in Okihiro syndrome (OS), which is characterised by forelimb defects and the eye disorder, Duane anom aly. OS patients forelim b defects range from subtle thumb abnormalities to trunca...

The cardiac conduction system is an anatomically discrete segment of specialized myocardium that initiates and propagates electrical impulses to coordinate myocardial contraction. To define the molecular composition of the mouse ventricular conduction system we used microdissection and transcriptional profiling by serial analysis of gene expression (SAGE). Conduction-system-specific expression ...

We report a critical role for the T-box transcription factor Tbx5 in development and maturation of the cardiac conduction system. We find that Tbx5 is expressed throughout the central conduction system, including the atrioventricular bundle and bundle branch conduction system. Tbx5 haploinsufficiency in mice (Tbx5(del/+)), a model of human Holt-Oram syndrome, caused distinct morphological and f...

MicroRNAs (miRNAs) are small non-coding RNAs that play an important role in the post-transcriptional regulation of gene expression. miRNAs are involved in the regulation of many biological processes such as differentiation, apoptosis, and cell proliferation. miRNAs are expressed in embryonic, postnatal, and adult hearts, and they have a key role in the regulation of gene expression during cardi...

Atrial fibrillation (AF), the most common type of cardiac rhythm disturbance encountered in clinical practice, is associated with substantially increased morbidity and mortality. Aggregating evidence demonstrates that abnormal cardiovascular development is involved in the pathogenesis of AF. A recent study has revealed that the TBX5 gene, which encodes a T-box transcription factor key to cardio...

We previously reported that mice lacking the hairy-related basic helix-loop-helix (bHLH) transcription factor CHF1/Hey2 develop a thin-walled left ventricle. To explore the basis for this phenotype, we examined regional gene expression patterns in the developing myocardium. We found that atrial natriuretic factor (ANF), which is normally expressed in the atria and trabeculae and is restricted f...

Several factors have been proposed as contributors to interfamilial and intrafamilial phenotypic variability in autosomal dominant disorders, including allelic variation, modifier genes, environmental factors and complex genetic and environmental interactions. However, regardless of the similarity of genetic background and environmental factors, asymmetric limb or trunk anomalies in a single in...

Morphological differences between forelimbs and hindlimbs are thought to be regulated by Tbx5 expressed in the forelimb and Tbx4 and Pitx1 expressed in the hindlimb. Gene deletion and misexpression experiments have suggested that these factors have two distinct functions during limb development: the initiation and/or maintenance of limb outgrowth and the specification of limb-specific morpholog...